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# c3 trig identities help watch

1. can someone help me with this question:

find possible values of sintheta if cos2theta=23/25
2. Double angle formula:

Rewrite cos 2theta as 1 - 2 (sin theta)^2
3. (Original post by nyeem)
can someone help me with this question:

find possible values of sintheta if cos2theta=23/25
Use the identity: .
So you have . Now just rearrange to make the subject. Be wary of the sign of your result.
4. thanks i just remembered that identity

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